Heretofore, a fluid pressure device (for example, a relief valve, a pressure reducing valve, etc.) has been used to control the flow rate of a pressure fluid that flows through a flow path.
In a relief valve, which functions as a fluid pressure device of this type, for example, as disclosed in Japanese Laid-Open Patent Publication No. 2006-329353, a valve plug is provided that is movable in an axial direction in the interior of a main valve body. The valve plug is made up from a shaft, and an umbrella-shaped valve plug member that is formed on one end of the shaft, the valve plug member being arranged inside a flow path through which a fluid flows. A seal member is disposed through an annular groove on the outer circumference of the valve plug member, such that when the valve plug is moved, by abutment of the seal member against an inner circumferential surface of the main valve body, communication between a fluid inlet passage and a relief passage that constitute parts of the flow path is blocked.
With the valve structure of the above-described relief valve, for example, although the seal member is mounted in the annular groove of the valve plug, in the event that fluid flows in between the annular groove and the seal member, there is a concern that the seal member can be made to peel away and separate from the annular groove by the fluid. As a result, it is thought that the sealing performance, i.e., the capability of the seal member to seal the fluid, tends to be lowered. With the aim of preventing peeling away of this type of seal member, it has been considered to bond the seal member with respect to the annular groove using an adhesive or the like. However, in this case, a step is required to apply or coat the adhesive, which increases the number of assembly steps needed to assemble the relief valve.